Proline

[peacefulheart]

1. Proline interrupts tha alpha helix struture of myoglobin because when When proline is bound as an amide in a peptide bond, its nitrogen is not bound to any hydrogen, meaning it cannot act as a hydrogen bond donor, but can be a hydrogen bond acceptor. But hydrogen bond acceptor can still hydrogen bond ?

2. Does the special structure of proline helps the formation of Beta-sheets of secondary structure or disrupt it .

3. Thanks a lot.

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[adrakdavra]

When proline is in a peptide bond, it does not have a hydrogen on the α amino group, so it cannot donate a hydrogen bond to stabilize an α helix or a β sheet. It is often said, inaccurately, that proline cannot exist in an α helix. When proline is found in an α helix, the helix will have a slight bend due to the lack of the hydrogen bond.

 

[TieuBachHo]

1. Proline interrupts tha alpha helix struture of myoglobin because when When proline is bound as an amide in a peptide bond, its nitrogen is not bound to any hydrogen, meaning it cannot act as a hydrogen bond donor, but can be a hydrogen bond acceptor. But hydrogen bond acceptor can still hydrogen bond ?
--- However, the steric hindrance of a proline in peptides prohibits it from H-bond with other AAs. In addition to lacking a hydrogen bond, the rigid structure of proline makes it difficult to have a N-Calpha rotation in an alpha helix (which means that the alpha helix's stability decreases as more and more proline are added but not impossible)

2. Does the special structure of proline helps the formation of Beta-sheets of secondary structure or disrupt it?
--- The cis-proline helps with 180-degree Beta turns.